Roller bearing mounted barrel for a machine gun



Nov. 10, 1964 J. L. LOCHHEAD ROLLER BEARING MOUNTED BARREL FOR A MACHINE GUN 2 Sheets-Sheet 1' Filed 001;. 16, 1963 INVENTOR. I Isl-m L -Luchhe mi Nov. 10, 1964 J. L. LOCHHEAD 3,156,153

ROLLER BEARING MOUNTED BARREL FOR A MACHINE cum Filed Oct. 16, 1963 2 Sheets-Sheet 2 INVENTOR Icahn L-Luc11hen cf W b-bv KW States The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to machine guns and pertains more particularly to means for mounting the barrel.

With machine guns having reciprocal barrels, trouble is oftentimes encountered respective to the barrel mountings. The conventional method for slidingly supporting the barrel is to install a bushing between the barrel and the barrel jacket and forming a bearing area on the barrel. During prolonged firing bursts, the barrel gets red hot and, therefore, expands considerably under the heat. To provide for this expansion, a clearance of considerable dimension must be provided between the barrel and bushing otherwise the bearing surface on the barrel and the inside of the bushing will seize causing malfunction of the gun. But because of this clearance, the front end of the barrel is permitted to whip, when the barrel is cold, reducing its accuracy.

Moreover, in such barrel mountings, the frictional contact between the barrel and bushing becomes a major problem when the weapon fires low pressure ammunition where the recoil forces are barely suificient to energize the operating mechanism. Also, the large clearance between the barrel and bushing permits foreign material to enter therebetween and cause malfunction.

It is, therefore, one object of this invention to provide for machine guns with reciprocal barrels a roller bearingtype mounting which reduces the bearing surfaces on which the barrel moves and which spaces the bearing surfaces from the barrel bore so as to be less effected by discharge heat than the bushing-type mountings, thereby permitting closer tolerances between the barrel and supporting barrel structure, for better accuracy, and reducing to a minimum the frictional loss of power.

It is a further object of this invention to provide a barrel mounting which permits quick and easy exchange of barrels.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a longitudinally sectioned side view of the front end of a machine gun showing the barrel mounted according to this invention;

FIG. 2 is a view taken along line 2-2 of FIG. 1;

FIG. 3 is a view taken along line 3-3 of FIG. 1;

FIG. 4 is a longitudinally sectioned side view showing the barrel unlatched from the receiver and pulled forwardly in the first step of removal from the gun; and

FIG. 5 is a similar view showing the second and final step of the barrel removal.

Shown in the figures is a machine gun 12 With a reciprocal barrel 14, The outside of barrel 14 is provided with a cylindrical section 16 terminated at the front end by an annular shoulder 18 and a forwardly tapering section 20 which extends forwardly from the annular shoulder. A pair of axles 22 extend diametrically from cylindrical section 16 to provide rolling support for a pair of rollers 24 respectively mounted thereon. A sleeve 26, essentially square in cross-section, is fixedly mounted on Patented Nov. 10., 1964 tapered section 18 and extending laterally from opposite sides of the sleeve is a pair of shafts 28 which are disposed parallel to the axles 22. Each of the shafts 23 rotatingly mounts a pair of roller bearings including an inner bearing 30 and an outer bearing 31 of similar diameter.

Extending forwardly of a receiver 32 is a barrel support 34 of U-shaped configuration in cross-section. Barrel support 34 is terminated at the front end by a pair of arms 36 which are extensions of the sides of the barrel support and are laterally spaced in parallel relationship. Arms 36 are each provided with a flange 38 which extends along the bottom of the inner sides thereof to double the thickness of the arms thereat. Extending rear- Wardly into each of the arms 36 from. the front end thereof is a longitudinally elongated recess 40. The bottom side of each of the recesses 40 is located below the top side of the associated flange 38 to provide a clearance therebetween and form along the top of each of the flanges a lower raceway 42 which is contacted by the respective one of the inner roller bearings 30. The top sides of the recesses 40 are parallel with the corresponding ones of the lower raceways 42 and form upper raceways 44 which are contacted by the respective ones of the outer roller bearings 31, whereby each of the roller bearings has contact with only one of the raceways to provide for rolling contact therewith.

A rail 46 extends into barrel support 34 from each side thereof for rolling contact by the rollers 34. Extending transversely between the sides of receiver 32 above cylindrical section 16 is a shaft 48 which rotatingly mounts a spool 50 having a concave annular channel 51 with the same radius as the cylindrical section to matingly make contact therewith for maintaining rollers 24 in contact with rails 46 and assist in restraining lateral displacement of barrel 14.

Barrel 14 is releasably secured in machine gun 12 by a latch 52 which is pivotally mounted on receiver 32 for engaging contact with shoulder 18. Latch 52 also provides the front stop for barrel 14 in its forward stroke. Barrel 14 is easily replaced in the field by actuating latch 52 free of shoulder 18 and then pulling forwardly on the barrel until roller bearings 30 and 31 are clear of recesses (see FIG. 4) and the rear end of the barrel is located in barrel support 34 so that the rear end may be tilted upwardly, as shown in FIG. 5, and the barrel ejected.

From the foregoing it is clearly apparent that barrel 14 reciprocates with a minimum of frictional loss to conserve recoil energy and that the bearing surfaces on which the barrel rolls are spaced therefrom to reduce considerably the eifect of barrel heat, whereby the tolerances between the bearing surfaces can be reduced to a minimum, providing for greater accuracy and making seizure almost impossible. Moreover, the nature of the roller bearing mounting disclosed herein provides for easy replacement of the barrel.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claim is intended to include such variations.

1 claim:

In a machine gun having a receiver, a barrel support of U-shaped configuration in cross-section extending for- Wardly from the receiver, a reciprocal barrel, a pair of axles extending diametrically from said barrel adjacent the rear end thereof, a pair of rollers respectively mounted on said axles, rails formed in the receiver for supporting contact by said rollers, a pair of shafts extending diametrically from said barrel forwardly of said axles and parallel therewith, an inner and an outer roller bearing mounted on each of said shafts, a pair of arms ex- 3 a 4 tending respectively forward from the sides of said bar- References Cited in the file of this patent rel support-,- a flange formed along the inside of each of said arms, a recess extending longitudinally into each of UNITED STATES PATENTS said arms from the front end thereof, an upper raceway 1,234,575 Schneider July 24, 1917 formed along the upper side of each of said recesses for 5 2 213 953 Conlon Sept 10 1940 the related one of said outer roller bearings, and a lower 28518O9 Colby Sept 1958 raceway formed along the top side of each of said flanges for the related ones of said inner roller bearings. t 

